Method and apparatus for the continuous carbonization of coal

ABSTRACT

A CONTINUOUS COAL CARBONIZATION SYSTEM INCLUDES AUTOMATED BELT CONVEYING APPARATUS THAT CARRIES COAL THROUGH AN ELONGATE COKING CHAMBER WHEREIN THE TEMPERATURE VARIES SO AS TO CHANGE THE COAL INTO COKE.

G. M. BRETZ July 6, 1971 METHOD AND APPARATUS FOR THE CONTINUOUS CARBONIZATION OF COAL Filed Dec. 12, 1968 3 Sheets-Sheet 1 INVFNTOR. GFOPGE M. 5.95 rz FIG. 2

VYZZWIKVL METHOD AND APPARATUS FOR THE CONTINUOUS CARBONIZATION OF COAL Filed Dec. 12, 1968 G. M. BRETZ July 6, 1971 5 Sheets-Sheet FIG. 4

FIG. 3

INVFNTOR GEO/ 6E M BRETZ July 6, 1971 G. M. BRETZ 3,591,462

METHOD AND APPARATUS FOR THE CONTINUOUS CARBONIZATION OF COAL Filed Dec 12, 1968 3 Sheets-Sheet 3 7 "6 I //7 W9 PW/IQ L5 :4 r (0 /Z/ /0 Q [2/ /25 27 I NVENTOR GEORGE M 5/?57'2 filler/leg United States Patent O US. Cl. 201-15 9 Claims ABSTRACT OF THE DISCLOSURE -A continuous coal carbonization system includes automated belt conveying apparatus that carries coal through an elongate coking chamber wherein the temperature varies so as to change the coal into coke.

BACKGROUND OF THE INVENTION Coal carbonization equipment in the form of horizontal coke oven batteries appears to be reaching a plateau with respect to the size of equipment, coking time, construction materials, product quality, and ease of automation. The size of the coking chambers has just about reached a maximum, and any attempt to increase the size of the coking chamber itself will not be as beneficial as might be expected. The type of metallurgical coke produced in such coke. ovens is excellent, but a conventional coke oven battery is an enormously expensive capital investment. Means to produce equivalent product at less cost are continually being sought.

Modern blast furnace operation requires a closely-sized, strong coke and burden materials with a minimum of fines, and fine-sized, beneficiated iron ores must be formed into larger, closely-sized, strong, aggregative forms such as pellets.

Heretofore, the continuous coking of coal in a vertical retort has been tried, but the coke thereby produced has been of poor quality due, in part, to the fact that as thecoal flows down inside the vertical retort and turns to coke, the coal-coke is under tension which separates the coal particles instead of compacting them to make a closely grained coke product.

How the equipment and method of the present invention overcomes the disadvantages of the prior art apparatus and produces a satisfactory coke in an efficient and less costly manner, is set forth in the following description of an embodiment of the invention.

SUMMARY OF THE INVENTION The method of the invention includes force feeding coal onto a grate traveling through a combustion chamber,

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in the drawings wherein: FIG. 1 is a schematic isometric partially exploded view of one embodiment of apparatus in accordance with the invention;

FIG. 2 is a view along line IIII of FIG. 1;

FIG. 3 is a schematic isometric view, partly cut away, of another embodiment of apparatus in accordance with the invention;

FIG. 4 is a plan view of the apparatus of FIG. 3;

FIG. 5 is a sectional view along line VV of FIG. 4;

FIG. 6 is a schematic view of a modification of one end of the apparatus of FIGS. 1 and 4; and

FIG. 7 is a view along line VII-VII of FIG. 6.

DETAILED DESCRIPTION FIG. 1 illustrates one embodiment of apparatus 11 for continuously coking coal in accordance with the invention that includes: a traveling grate portion 13; a combustion chamber portion 15; collecting bin or receptacle 17; and an exhaust stack 19.

:T he traveling grate portion 13 is comprised of a plurality of rectangular flat refractory shapes 21 that are individually secured to links 23 at each side of the shape 21 (FIG. 2); the links 23 at each side being interconnected in the usual manner to form endless chains that pass over pairs of end sprockets 25, one of which sprockets is powered in a conventional manner by a source of power 27, such as an electric motor or the like.

The links 23 and the shapes 21 are supported along the length of the traveling grate portion 13 by spaced apart channels 29, or in any other suitable manner.

Each individual refractory shape 21 also includes a pair of side plates 31 that project above the top surface of the shape 21 and that are coextensive in length with the sides of the refractory shape.

Between the end sprockets 25 and extending along the length of the traveling grate 13, there are a plurality of wind boxes 33 disposed beneath the refractory shapes 21, as suggested in FIG. 2. Each wind box 33, through a system of conduits 35, is provided with a mixture of fluid oxidant, that may be oxygen or oxygen enriched air. The fluid oxidant is directed to flow upwardly from the wind boxes 33 through the refractory shapes 21 so as to partially oxidize, under strict control, coal 37 on the traveling grate 13.

The combustion chamber 15 comprises inner 39 and outer 41 spaced apart side walls which are disposed adjacent to and along the longitudinal sides of the traveling grate 13. A top 43 covers the space between the inner side walls 39 to form a coking chamber 45, and a top 47 covers the space between the outer side walls 41 to form a gas passage 49 between the inner walls 39, 43 and outer walls 41, 47. The inner walls 39, 43 and outer walls 41, 47 are constructed of relatively thin, high density, super refractory material that is capable of withstanding temperatures hot enough to transform the coal 37 into coke.

The side walls 39, 41 are supported on horizontally extending concrete pads or footings 51 that are grounded, or otherwise fixed to suitable structure, and that are located alongside the traveling grate 13, about as shown in FIGS. 1 and 2.

Between the inner 39 and outer 41 side walls, there are a plurality of spaced-apart pairs of opposed side baffles 53 that are also constructed of refractory material like the wall material. The tops of the side baffles 53 are substantially flush with the upper surface of the top 43, and

the bottom of the side baffles 53 abuts the concrete pad or footing 51.

There are also top baflies 57 extending laterally between the outer side walls 41, vertically between the tops 43 and 47, and down the side walls 39. They are passageways 55 'between the lower end of the baffles 57 and the concrete pad 51. The top baflles 57 intercept the longitudinal flow of gases in the combustion chamber 15 (as shown by arrows in FIG. 1) and direct the gases down the side walls, through the opening 5, and thence upwardly to the top again. In this manner the gases heat substantially all of the side walls of the coking chamber 45, as in a conventional coke oven.

After the gases have traversed the passages in the combustion chamber 15, the gases flow into a hood 59 which is surmounted by the exhaust stack 19 which carries the gases to atmosphere, or to a gas cleaning apparatus. The exhaust hood 59 may be lined with refractory material, or it may be constructed as a water jacket in a known manner, or as preferred.

The end of the combustion chamber adjacent the exhaust hood 59 abuts a coal feed hopper 61 that is adapted to receive and to dispense coal onto the traveling grate 13. The coal feed hopper 61, in one embodiment of the invention, includes a rectangular shaped upper portion 63 that is integrally formed with, or suitably attached to, a lower portion 65 having a pair of converging opposed sides. Coal may be delivered to the feed hopper 61 in any suitable manner, and the discharge of coal from the feed hopper may be regulated in any suitable manner, such as by a rotary vane feeder, a sliding gate, or the like.

FIG. 6 illustrates another type of coal feed hopper 67 which includes a rectangular upper portion 69 into which coal is delivered in a known manner and a plurality of rectangular shaped pistons 71 (FIG. 7 shows six such pistons) that are connected in two groups of three to power-driven crank shafts 73, 75. Those skilled in the art will recognize that, while six pistons 71 are illustrated in the embodiment of the invention shown in FIG. 7, more or less number of pistons 71 may be used if desired or preferred. Each crank shaft 73, 75 may be rotated by conventional means (not shown).

Coal in the rectangular hopper 61 gravitates into the lower zone of the hopper from which it is pushed down and inclined surface 77 onto the traveling grate 13 by the reciprocating pistons 71.

Hence, coal from the feed hopper 67 becomes compacted by the action of the pistons 71 so that when the coal discharges onto the traveling grate it is already compacted in much the same way as the coal in a horizontal coke oven chamber.

At the opposite end of the traveling grate 13, the com bustion chamber 15 is closed by a burner header wall 79 that has a generally inverted U-shape. The header wall 79 is hollow and supports a plurality of horizontally extending, conventional jet fuel burners 81.

In a particular application, the discharge ends of the jet fuel burners lie practically flush with the inside surface of the walls of the inner combustion chamber. In design, such injection burners would be similar to an ASME long-radius nozzle or Borda orifice, and they would be constructed of special ceramic shapes.

One wall 81 of the header wall 79 that faces the combustion chamber 15 is refractory lined so as to resist the heat generated within the combustion chamber. The other walls of the header wall 79 may be refractory lined, or they may be water cooled, as by a water jacket, if preferred.

The collecting bin 17 is located adjacent the burner header wall 79 and includes a covered cylindrical main body portion 85 that is integrally formed with a frustoconical lower portion 87. The lower end of the frustoconical portion 87 is attached to a rotary dispensing apparatus 89, such as a rotary vane feeder, that discharges coke from the collecting bin 17 Onto a moving conveyor belt 91.

A vertical conduit 93 is axially arranged in the collecting bin 17 and is spaced apart a short distance from the top of the rotary feeder 89 to permit gases within the collecting bin 17 to flow upwardly in the conduit 93, and out of the collecting bin 17. A side outlet conduit 95 fluidly connects the vertical axial conduit 93 with the burner header walls 79, and an adjustable damper 97 of the butterfly type, is positioned within the vertical conduit 93 at a location just above the side outlet conduit 95. This butterfly valve damper 97 permits regulation of the amount of gases that pass through the side conduit 95 and also the amount of gases that pass directly upward through the vertical conduit 93.

The inner surface of the collecting bin 17 is refractory lined in a known manner. Of course, the 'walls of the bin 17 may be water cooled, as by water jackets, in a known manner if desired.

The apparatus 1 1 is operated in the following manner. Coal 37 is delivered continuously to the hopper 63, and the traveling grate 13 moves continuously in a direction of the arrow A through the combustion chamber 15. Fuel is burned with air or heated gases, or oxygen-enriched air at the burners 81, and the heated gases of combustion are directed by the baffles 53, 55 over the surface of the inner walls 39. As in a conventional coke oven battery, the heat in the combustion chamber 15 is transmitted through the walls of the chamber to the inner coking chamber 45, and the coal therein is transformed into coke as it travels along the traveling grate. As necessary, air or oxygen-enriched air may be delivered by the conduit system 35 to the wind boxes 33 in controlled quantities; the several wind boxes being each provided with a separate control mechanism of a conventional type (not shown).

Partial quenching of the hot coke may take place in the collecting bin 17 by means of water emitted from a plurality of sprays 100, only one being suggested in FIG. 1. The gases exit the combustion chamber, along with the hot coke, mix with the quenching steam in the combustion chamber and pass upwardly through the centrally located vertical conduit. A portion of these gases is recycled into the side outlet conduit by adjusting the damper, and these diverted gases mix with fuel burned in the burners.

To alleviate the formation of carbon deposits, which occur at any constant coal feed rate and recycle gas rate, the gas flow to the burners may be varied cyclically from 50-120% of the stoichiometric combustion requirement. The gases leaving the combustion chamber may be used as produced, or these gases may be combined with the rich gases flowing upwardly in the central vertical conduit. If preferred, an overfire oxidant stream, introduced into the coking chamber near the fired end and above the coal, may be used.

The apparatus 99 of FIGS. 3-5 is another embodiment of the invention, and such embodiment is so much like that shown in FIGS. 1, 2, 6 and 7 that only the differences are illustrated in FIGS. 3-5. In FIG. 3, a traveling grate 101 moves continuously in the direction of the arrow B and carries coal through a coking chamber 103 (FIG. 5) that is constructed of refractory side walls 105 and a top 107, disposed about as shown in FIGS. 4 and 5. The coking chamber 103 is surrounded in spaced apart relation, as in the embodiment of the invention shown in FIGS. 1 and 2, by refractory walls 109 and a top 111 that forms an inner combustion chamber 113. Both the side walls 105 and 109 rest on and are supported by concrete pads or footings 115.

The outer walls i109 have a plurality of openings 117 therethrough arranged alternately on opposite sides of the apparatus, as suggested in FIGS. 3 and 4. In each opening 117 there is a jet injection burner 119 that is similar to the burner 81 shown in FIG. 1, and that is supplied with oxygen-enriched air from a supply header 121.

The outer walls 109 and the top 111 are also surrounded by other spaced apart side walls 123 and top 125, that form a second or outer combustion chamber or gas passage 127.

From FIG. 4 it will be noticed that, at the right-hand end of the apparatus 99, there are two vertical refractory valves or vanes 129 that are hinged about vertical axes at the end of the side walls 109. The refractory vertical valves or vanes 129 are wide enough and tall enough so that, when they are disposed perpendicularly to the traveling grate 101, as in FIG. 4, they close the right-hand end of the first combustion chamber or gas passage 113.

The apparatus 99 may be associated with a coal feed hopper 61 or 67, collecting bin 17, exhaust hood 59, rotary feeder 89 and conveyor belt 91, like those described hereinbefore. In operation of the apparatus 99, the primary carbonization gas, liberated from the coal during the coking process, passes into either one or both of the two combustion chambers 1113, 127. The gas flow path is diverted into either or both of the passages by changing the position of the two vertically oriented ceramic valves or vanes 129.

Oxygen-enriched air, carried in the supply header 121, is introduced into the throats of the jet burners 119; flame holders being provided on the downstream side of these burners in a normal manner.

Carbonization gas generated in the coking chamber passes into the collecting bin and such gas, along with steam generated during quenching of the coke, flows into the second or outer combustion chamber 127. The vertical refractory valves or vanes 129 are positioned, as shown in FIG. 4, to prevent maximum gas flow into the first or inner combustion chamber 113. It should be understood that the vertical refractory valves or vanes 129 need not fit tightly across the ends of the passages because a small amount of gas flow in either of the passages creates no serious problem in carrying out the method of the invention.

Then, fuel gas aspirated into the burner 119 from the combustion chamber 127 mixes with oxygen-enriched air and the mixture burns in the inner combustion chamber 113 to heat the walls of the coking chamber.

The heat of combustion resulting from the burning of the aforementioned gas mixture heats the walls 105 and top 107 of the coking chamber 45 and the coal therein is transformed into coke as the coal moves along the traveling grate.

When a predetermined maximum temperature is obtained in the inner combustion chamber 113, the vertical refractory valves or vanes 129 may be rotated or pivoted about their vertical axes by apparatus 130 so that carbonization gases, along with the quenching steam, now flow into the inner combustion chamber 113. Simultaneously with this reversal of the position of the refractory valves or vanes 129, oxidant gases flowing to the jet injection burners are reduced to a set minimum value by known control valve equipment, and cyclical reforming of the carbonization gases admixed with quenching steam commences. The reforming portion of the cycle proceeds until the chamber temperature is reduced to a preselected minimum value. Thereafter, a gradual increase in the flow of the oxidant of the jet burners is started and simultaneously the vertical refractory vanes are reversely pivoted. The jet oxygen fiow is increased to a preselected maximum value and heating of the walls of the coking chamber commences once again.

The inner combustion chamber is rapidly reheated and any carbon deposited on the walls during the previous cycle is quickly burned off. The inner combustion chamber is allowed to heat up to a predetermined maximum temperature again and then the heating and reversing cycle is repeated.

Those skilled in the art will understand that the side 53 and top 57 bafiles described hereinbefore with respect to the apparatus of FIGS. 1 and 2, are also associated with the structure 99 shown in FIGS. 3-5.

In both embodiments of the invention, the recycle jet injection burners are shown in a common horizontal plane, but the burner locations depend on the need to achieve uniform heating of the carbonization chamber walls and the burner locations may be varied as desired.

Further, those skilled in the art will recognize many significant features and advantages in the present invention among which are: coke production is not cyclical, but is continuous. The coal charge material is heated more uniformly and more rapidly than in the standard horizontal coke oven. Consequently, productivity is increased.

The process of the invention may be easily automated both in terms of feed and product removal, resulting in reduced operating costs per ton of coke produced.

The feed flow of coal to, and the product flow of coke from, the apparatus may easily be controlled and operated independently: for example, the rotary vanes, the ram feeder, the moving chain grate, and the coke removal rotary feeder may be operated independently, or the foregoing units may be interlocked with a program controller.

The initial capital investment per cubic foot of production capacity is significantly less than that required for a conventional horizontal coke oven battery.

The process is easily adjusted to effectively use a large variety of coals; those known as good coking coals and those known as poor coking coals.

The coal discharged from the hopper equipped with reciprocating pistons is compacted, wherefore better coke is obtained.

I claim:

1. Method for continuously coking coal comprising the steps:

(a) depositing coal continuously onto a traveling grate;

(b) moving the grate and the coal through a coking chamber;

(c) heating the walls of said coking chamber to effect coking of the coal within said coking chamber;

(d) discharging coke from said traveling grate into a receptacle;

(e) quenching said coke in said receptacle;

(f) passing the gases liberated from said coal during coking into said receptacle;

(g) mixing oxygen-enriched air with said liberated gases and burning such mixture to heat the walls of said combustion chamber; and

(h) removing quenched coke from said receptacle.

2. The method of claim 1 including the steps:

(a) directing the heat of combustion of said oxygenenriched air and liberated gases axially along the length of said combustion chamber; and

(b) providing baffles on said walls of said combustion chamber to effect directng the heat of combuston over substantally all of the surface of said combustion chamber.

3. The method of claim 1 wherein:

(a) depositing said coal includes the step of (i) force feeding coal from a hopper onto said traveling grate.

4. The method for continuously coking coal comprising the steps:

(a) force feeding coal onto a traveling grate;

(b) passing said grate and coal through a coking chamber;

(c) heating the walls of said coking chamber to effect coking of the coal on said grate and generating coke oven gases;

((1) discharging said coke and gases into a receptacle;

(e) mixing a portion of said coke oven gases with oxygen-enriched air and burning the mixture of gases in a first passageway outside of said coking chamber to heat said coking chamber;

(f) diverting s a-id coke oven gases into a second passageway outside of said coking chamber;

(g) periodically terminating said burning of the gas mixture and diverting said coke oven gases into said first passageway; and

(h) periodically resuming the burning of said gas mixture on a cyclical basis to continuously produce coke.

5. The method of claim 4 including the steps of:

(a) quenching said coke in said receptacle; and

(b) baffling said first passageway to direct the heat of combustion over the surface of said coking chamber.

6. Apparatus for continuously coking coal comprising:

(a) a coal hopper for receivng coal;

(b) means for force feeding said coal onto (c) a traveling grate adapted for linear movement;

((1) a first wall covering said traveling grate and defining a coking chamber;

(e) a second wall located in spaced apart relation to said first wall and defining a combustion chamber between said walls;

(f) means to heat the coking chamber wall to produce coke and coke oven gas in said coking chamber;

(g) a receptacle adapted to receive coke and coke oven gases discharged from said traveling grate;

(h) means to divert a portion of said coke oven gases into said combustion chamber;

(i) means to mix oxygen-enriched air with the coke oven gases; and

(j) means for burning the gas mixture to heat said coking chamber walls.

7. The apparatus of claim 6 including:

(a) means for quenching said coke in said receptacle.

8. The apparatus of claim 7 including:

(a) a third wall located in spaced apart relation to said second wall and defining a gas passage between said first and second walls; and

(b) a vane positioned adjacent the end of said grate near said receptacle that is pivotable to divert said coke oven gases selectively into either said combustion chamber of said second passage.

9. The apparatus of claim 8 including:

(a) means to pivot said vane so as to close either said combustion chamber or said second passageway; and

(b) means to reduce said burning by regulating the flow of said oxygen-enriched air when said coke oven gases flow in said second passage.

References Cited UNITED STATES PATENTS NORMAN YUDKOFF, Primary Examiner D. EDWARDS, Assistant Examiner U.S. Cl. X.R. 

